Dual‐Strategy Enhancement of NIR Phosphors: Solid Solution Design and Flux Modulation

Abstract During the development process of near‐infrared pc‐LEDs, Cr ³⁺ ‐doped near‐infrared phosphors have demonstrated an instrumental role. This work proposes a new approach in which the combined effects of Bi ³⁺ ‐La ³⁺ solid solution engineering and flux modulator regulation greatly increase the luminescence intensity and thermal stability of Cr ³⁺ . The solid solution Bi _2+y La _1‐y GaSb ₂ O ₁₁ :Cr ³⁺ has a tunable crystal structure, where the Bi/La ratio directly affects the luminescence intensity and thermal stability of Cr ³⁺ . Increased Bi ³⁺ substitution weakens crystal field splitting, inducing a systematic blueshift of emission peaks from 855 to 840 nm. Furthermore, optimized flux doping types and concentrations provide secondary enhancement of near‐infrared emission intensity. Finally, the near‐infrared phosphor‐converted LED (pc‐LED) device, fabricated by integrating Bi _2.8 La _0.2 GaSb ₂ O ₁₁ :Cr ³⁺ with a 460 nm blue LED chip, exhibits stable near‐infrared output and demonstrates outstanding performance in applications such as biological tissue imaging, organic compound analysis, and information encryption. This study not only provides a series of novel Cr ³⁺ ‐activated near‐infrared phosphors but also offers enhanced strategies and application paradigms for tunable Cr ³⁺ emission.